Sympathomimetics · Pharmacology

What is the chemical structural difference between catecholamines and non-catecholamines?

  1. Non-catecholamines lack the 3,4-dihydroxybenzene (catechol) ring
  2. Catecholamines are more lipid-soluble
  3. Non-catecholamines are always rapidly destroyed by the enzyme COMT
  4. Catecholamines have a longer half-life
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Correct answer: Non-catecholamines lack the 3,4-dihydroxybenzene (catechol) ring

Catecholamines possess a catechol ring (benzene with two hydroxyl groups), making them substrates for COMT and giving them low oral bioavailability and short durations. Non-catecholamines lack these hydroxyl groups, making them resistant to COMT and often more effective when taken orally.

Difficulty: Medium Question 18 of 20

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